Magnetic material



166. co-MPosmous, comma 0R PLAsnc May 15, 1928.

1,669,644 J. w. ANDREWS MAGNETIC MAT Filed Am il 24. 1926 Wren/0k J0; VIM/Mew Examimr Patented May 15, 192sf /l 1,669,644 UNITED STATES PATENT OFFICE.

JOHN WENDELL ANDREWS, OF CHICAGO, ILLINOIS, ASSIGNOR TO WESTERN ELECTRIC I comm, INCORPORATED, OF NEW YORK, N. Y., A. CORPORATION OF NEW YORK.

MAGNETIC MATERIAL.

Application med April 24, 1920. Serial No. 104,482.

This invention relates to magnetic mateployed is preferably pre ared from a nickel rials and magnet cores, and more especially iron allo common y re erred to as efito magnet cores for inductance units to be which is treated in a manner more used in telephone circuits and their method u y described in the copending application of red tion, of C. P. Beath and H. M. E. Heinicke, Serial 60 he principal object of the invention is No. 101,179, filed April 10, 1926, to reduce the production of a magnetic element posthe alloy to a finely divided form. Experisessing to a high'degree t ose electrical, magence has proven that where low eddy current netic and physical characteristics which losses are desired it is essential that the parmake it highly desirable in electrical signalticles be of small size and preferably of such 65 ling apparatus, particularly in apparatus size that all of the particles will readily pass employed in circuits carrymg currents of through what is generally known as a 200 hi h frequencies, mesh screen. According to one embodiment n accordance with one embodiment, the of the invention, the alloy is prepared by present invention contemplates the construcmelting approximately 7 8 partsof nickel tion of-magnet cores of a ma neticmaterial and 21% arts of iron in an oxidizing atmosreduced to a finely, divided form comblned phere an pouring the resulting alloy into a with a suitable insulatin material and mold. When prepared according to the bound in a compact ir-ass v a suita e bindforegoing process, the resulting alloy will i ore specifically, the man be exceedingly brittle and is therefore par- 7 tion contemplates the formation of magnet ticularly adapted to be reduced to a finely cores of a nickel iron allo in finel divided divided or dust form from which the finished form in WHICH the roportionso its concores are molded. I stituents are more t an 25% of nickel and After the ingots are obtained they are suc- 25 the remainder principally iron, and in a cessi'vely passed while hot throu h progresform which has proven satisfactory the" sively reducing rolls which formt e alloy innickel content being approximately 78 72; to flat slabs approximately one-quarter of an of the whole. 'The metal particles are inch thick. By the hot rolling process the enveloped with a primary coating of an insize of the crystalline structure is materially sulating material such as sodium silicate@ reduced, and since the disintegration of the 85 chromic cid the coated particles are thenmaterial takes lace mainly at the or stal gtreated with a bindin medium such as a boundaries, smal crystals are highly esira, thetic resi and tlie insulated particles able in order to have a satisfactory yield of W are formed mto cores at a temperature and dust. The rolled slabs are broken into short under a pressure suificient to form the matepieces and are then crushed in a jaw crusher 9o rial into a homogeneous solid. ammer mill, or any other suitable t pe o It is believed that the invention will be apparatus in which a further re uotion clearly understood from the followin deoccurs. The material after being passed tailed description of one embodiment t erethrough the aw crusher is subsequently 40 of and from the accompanying drawing, in rolled in a bal mill until it is reduced to a 95 which o fine dust. The dust is sieved throu h a 200 Fig. 1 is a perspective view of a section of mesh sieve and any residue is reme ted and a loading coil core made in accordance with the foregoing operation is repeated to again the resent invention, and reduce t e material to a finely divided form.

Fig. 2shows a pluralit of these sections Prior to the addition of the insulating 100 assembled to form a comp eted core. material, the finely divided articles of the It will be understood, however, that this nickel iron alloy are anneale at a temperais merely illustrative and the-invention is ture of approximately 400 .C. to 900 C. not limited to the production of this form It isthen necessary to again reduce the of core but is adapted to the roduction of annealed alloy which 'is now in the form of 105 elements of magnetiq partic es of many a cake to a finely divided form, after which forms. it is mixed with the insulator.

In carrying out the present invention, the According to one form of the invention,

magnetic material is prepared in the followthe insulator for the dust partielesis preing mannerz The magnetic material empared in the following manner: A thm solu- 1m comma R Foam Y i -heating infig iin mil ma enals such as na ura resin, aste 0 ans or ry coa ed dirst' particks are then mixed with about 5% ofa artiall cured s nthctic p resin in the form 0% a very line powder and the mixture placed in a ring die where the resin is cured by means of pressure low enough not to greatly distort any of the irdlvidual dust particle?) and a tlcmperaturc to 0 approximately 165 and t e materia is formed into rings or cores. A few test rings may be made of dust insulated in the above manner and their I permeability measured. Should their permeability be too low, it may be increased by the addition (if a gredetermined amount of uninsulat sulat 'r o ressed into rings. The rings are removed mm the presses and a plurality of rings thus formed are then stacked coaxially to form a core on which the usual toroidal winding is applied, the number of such rings used depending u n the existing electrical charac- N teristics o the circuit with which the inductance units are to be associated.

It is advantageous to form the rings or cores under a low pressure because it is then unnecessa to: heat treat them after they 40 are presse into shape. Pressing the rings under high pressures tends to distort the individual dust particles beyond their elastic limit and as a result the hysteresis losses are increased and the ermeability is decreased in the finished rings, thereby necessitating annealin the rings after pressing t9 restore their esirable magnetic properties. Since when the rings are pressed under low pressure, theindividual particles. are, not distorted and the rings retain their desirable magnetic properties, subsequent annealing is unnry. 4 4

Although the rmalloy. particles have been described 8.8 35 tlon of sodium silicate and the coated particles treated with a synthetic resin it 1s, of course, to be understood that other insulators, such as chromic acid a mur ture oi 'EEfomic acid and sodium icate, maybe no use 0 cos I r 1c es or" e dust may be insulated by su rficiall oxidizin it by lead oximnwma Jsu s 1 ut-ed u for me syntheiic resm an still produce articles, the dust is thoroughly e ore it is 'of a ma etic material, an

eing coated with a solucores which are satisfactory from both a magnetic and electrical standpoint. Also other nickel iron alloy wit satisfactory results.

By usin an alloy of the proportions stated in-t e preceding paragraph and by following the foregoing method of insulating the individual alloy particles and forming the particles into cores or rings, magnet cores or rings are produced which have e xtremely desirable electrical characteristics with a minimum amount of materiabemloyed. By the use of such'cores or rings, inductance units having a desirable permeability with e ual or less total losses than units constructe according to previously known methods but with much less core vfillume and much less coil volume, are availa e.

What is claimed is:

1. As a'new article of manufacture, a magnetic substance consisting of finely d1- vided particles of a nickel iron alloy, an insulating coatin on the particles, and an 'infusible, insolu le binding material holding the particles in a compact mass.

2. As a new article of manufacture, a magnetic substance consisting of finely d1- -vided particles of a nickel iron alloy, an insulating coating of sodium silicate, and a binder of a synthetic resin holding the particles in a compact mass.

3. As a new article of manufacture, a magnetic substance consisting of finely d1- vided particles of an alloy comprising more than 25% nickel and the remainder principally iron, an insulating coatin of sodium silicate on the particles, and a inder of a synthetic resin holding the particles in a compact mass.

4. As a new article of manufacture, a magnetic substance consistin of articles an insulator comp of sodium silicate and a synthetic resin separating the particles.

\5. As a new article of manufacture, a magnetic substance consisting of particles of nick and the remainder princi ally iron,

and an insulator composed of sodium silicate and a synthetic resin separating the particles.

6. The method of makingmagnetic structures which consists in envelopin finely di- Vided particles of a nickel iron a oy with a coating of an insulating material, and

treating a mass of such insulated particles with a phenolic condensation product to bind them to ether. a 7. The mat 0d of making magnetic structures which consists in enveloping finely divided particles of an alloy comprising more than 25 %,n1cl rel and the ;remainder principally 11'011 with an insulating coating 01 1,ees,e 44 4 3 tures, which consists in enveloping particles of a' magnetic material with a coating of an insulating material, adding a synthetic resin to a mass of such insulated particles,- and treating the mass at a temperature and under a pressure suflicient to cause a transformation of the resin to form a homogeneous so g 10. The method of making magnetic structures which consists in enveloping finely 2 divided particles of a ferrous magnetic material with an insulating coating of sodium silicate, adding a synthetic resin to a mass of such insulated particles, and treating the mass at a temperature and under a premure sufiicient to cause a transformation of the resin to form a homogeneous solid.

11. The method of'making magnetic, struc-' tures, which consists in reducingan alloy comprising more than 25% nickel and the remainder principally iron to finely divided as particles, heating the part1cles,reducing the resulting product to finely divided particles, enveloping the particles with an insulating coating of sodium silicate, adding a synthetic resin to a mass of such insulated par- 40 ticles, and treating the mass at a temperature and under; a-pressure suflicient to cause a transformation of the resin to form a homo eneous solid.

12. The method of making magnetic structures, which consists in treatin -a mass of magnetic particles in finely dlvided form with a phenolic condensation producfiand subjecting said treated mass to heat and pressure to form a homogeneous solid andto to cure said phenolic con ensation product.

. 13. The method of making magnetic structures, which consists in treating a mass of ma etic particles in finely divided for'm wit a partially cured phenolic condensation product, and subjecting said treated mas to heat and pressure to form a homo eneous solid and to com letely cure said p enohc condensation pr uct.

In witness whereof, I hereunto subscribe my name this tenth da of April As D., 1926.

JOHN W'E ANDREWS. 

